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    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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    <script>
        //1 声明一个年龄变量
        let age 
        //2 赋值
        age = 18
        //3 输出变量
        console.log(age)

        //4 声明同时赋值 变量初始化
        let b = 100
        console.log(b)

        //5 声明多个变量
        let c, d = 20, e = 'jack'
        d = 21
        console.log(d, e)

        

    </script>
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